FIG. 4.

Total and silver positive macrophages recovered from bronchoalveolar lung lavage at 1, 7, 21, and 56 days following exposure. Number of macrophages recovered from BALF (A). Percent of silver positive macrophages that are positive for silver staining based on autometallography and light microscopy at × 40 magnification (B). Macrophages were scored depending on the intensity of silver staining as light, moderate, and heavy as shown in Supplementary Figure 1 (C). Compared with the 20 nm 1 day score, the 20 nm 7 day had a P = 0.096 and the 20 nm 21 day was P = 0.068. Asterisk (*), significantly different than citrate buffer at same timepoint; dagger (†), significantly different than 1 day timepoint for same particle type; double dagger (‡), significantly different than 20 nm AgNP at same timepoint; and delta (§), significantly different than 7 day timepoint for same particle type (P < 0.05) (n = 6).